dacscred(1) acquire and manage DACS credentials


dacscred [-dd dir] [-ll log_level] [-v] op [opargs]


This program is part of the DACS suite.

The dacscred utility supports simple DACS authentication, optionally storing the returned DACS identities securely for future use by non-browser applications. Basic maintenance operations are provided for this cache of credentials.

DACS per-user information, including the cache, is kept within a directory that must be owned by the user. Additionally, the directory must be accessible only by the user. DACS will refuse to use any per-user information if file permissions are inappropriate.

If this directory is not specified on the command line, the following is the default behaviour. If an environment variable named DACSDIR is available, its value is used for the name of this directory; otherwise, DACS will use a directory named .dacs in the user's home directory.

The contents of the cache file are encrypted. A password must be provided when the cache is created and before each subsequent access. Currently, AES-128-CFB is used along with a SHA1-based m[blue]HMACm[][1].


A jurisdiction may reject credentials that are used from an IP address that does not match the IP address from which the credentials were initially requested (see the VERIFY_IP configuration directive). This means that if a cache is moved to a different host, the credentials may be treated as invalid if they are used from that host.


The following command line flags are common to all operations:

-dd directory

The DACS directory to use instead of the default is directory.

-ll log_level

Set the debugging output level to log_level (see m[blue]dacs(1)m[][2]). The default level is warn.


The -v flag bumps the debugging output level to debug or (if repeated) trace.

The op argument specifies the operation to be performed. The following operations are available:

Try to authenticate as username by invoking m[blue]dacs_authenticatem[][3] at the URL auth-URL. username has the syntax [[federation]::]jurisdiction:username (the jurisdiction component of the name must be provided; see m[blue]dacs(1)m[][4]). An SSL connection is always used for this purpose.

If authentication is successful and the -s flag is not given, the (username, auth-URL) pair will be recorded; subsequent invocations of the command can omit the auth-URL argument if it is unchanged. If the -p flag is given, the user is prompted for a password to pass to dacs_authenticate; if -pf is given instead, a password is read from file (stdin is read if file is "-"). If aux is given, it is used as the value of the AUXILIARY argument to dacs_authenticate. The -caf (-ccf) flag identifies file as a file of CA certificates (client certificates) in PEM format, respectively; see m[blue]sslclient(1)m[][5].

New credentials replace old credentials in the cache. Credentials and authentication mappings in the cache are not automatically managed, so the cache may contain credentials that have expired.

The following example prompts the user for a password before trying to authenticate as DSS:smith:

% dacscred auth -p DSS:smith \

The following example might be used within a script to test if $passwd is the correct password for DSS:smith:

% echo $passwd | dacscred auth -s -pf - DSS:smith \

The exit status will be 0 only if the password is correct.

Delete all credentials with a name that matches a regular expression (see m[blue]regex(3)m[][6]).

Print all credentials to stdout that should be sent along with a service request to the given URL. If no URL is given, print all credentials in the cache. Note that these credentials represent DACS identities and should be kept secret.

List the names of all credentials in the cache, by default. This is equivalent to providing the cred argument. If the auth argument is given, a list of identities and the auth-URL arguments that were used to authenticate those identities is displayed. If a regex is given, the list is limited to those identities matched by it (cred behaviour) or those "usernameauth-URL" strings that match it (auth behaviour).

Change the password that protects the cache. The current password must first be provided.


The program exits 0 if everything was fine, 1 if an error occurred.


This command only supplies partial support for interacting with dacs_authenticate.


Distributed Systems Software (m[blue]www.dss.cam[][7])


Copyright2003-2013 Distributed Systems Software. See the m[blue]LICENSEm[][8] file that accompanies the distribution for licensing information.